Consequently, the GLP-1R agonist Ex4 is capable of modulating cocaine-related CPP memory, enhancing extinction, and weakening the cocaine-primed reinstatement by suppressing TLR4 over-expression within the hippocampus, similar to many studies revealing that extinction in substance abuse can be pharmacologically enhanced (Botreau et al., 2006; Paolone et al., 2009). Here, TLR4 is linked to substance abuse.